Method and apparatus for channel state information (csi) reporting

ABSTRACT

Methods and apparatuses for CSI reporting mechanisms are provided. A user equipment (UE) apparatus includes a transceiver and a processor. The transceiver is configured to receive configuration information for channel state information (CSI) reporting including a plurality of precoding codebook parameters. The processor is operably connected to the transceiver, and configured to determine, in response to receipt of the configuration information for the CSI reporting and the configuration information for the plurality of precoding codebook parameters, a first precoding matrix indicator (PMI) and a second PMI, wherein the first PMI includes one or two codebook indices. The transceiver is further configured to transmit the CSI reporting on an uplink channel, the CSI reporting including the determined first and second PMIs.

CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY

This application is a continuation of U.S. patent application Ser. No.15/966,235, filed Apr. 30, 2018, which is a continuation of U.S. patentapplication Ser. No. 15/146,807, filed May 4, 2016, now U.S. Pat. No.9,967,012, which claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application No. 62/157,828 filed May 6, 2015; andU.S. Provisional Patent Application No. 62/203,172 filed Aug. 10, 2015,the disclosures of which are herein incorporated by reference in theirentirety.

TECHNICAL FIELD

The present disclosure relates generally to transmission mode andchannel state information (CSI) reporting for multiple transmit antennaswhich includes two dimensional arrays. Such two dimensional arrays canbe associated with a type of multiple-input multiple-output (MIMO)system often termed “full-dimension” MIMO (FD-MIMO) or massive MIMO or3D-MIMO.

BACKGROUND

Wireless communication has been one of the most successful innovationsin modern history. The demand of wireless data traffic is rapidlyincreasing due to the growing popularity among consumers and businessesof smart phones and other mobile data devices, such as tablets, “notepad” computers, net books, eBook readers, and machine type of devices.To meet the high growth in mobile data traffic and support newapplications and deployments, improvements in radio interface efficiencyand coverage is of paramount importance.

A mobile device or user equipment can measure the quality of thedownlink channel and report this quality to a base station so that adetermination can be made regarding whether or not various parametersshould be adjusted during communication with the mobile device. Existingchannel quality reporting processes in wireless communications systemsdo not sufficiently accommodate reporting of channel state informationassociated with large, two dimensional array transmit antennas or, ingeneral, antenna array geometry which accommodates a large number ofantenna elements.

SUMMARY

Various embodiments of the present disclosure provide methods andapparatuses for codebook design and signaling.

In one embodiment, a user equipment (UE) is provided. The UE includes atransceiver and a processor. The transceiver is configured to receiveconfiguration information for a channel state information (CSI)reporting including a plurality of precoding codebook parameters. Theprocessor is operably connected to the transceiver, and configured todetermine, in response to receipt of the configuration information forthe CSI reporting and the configuration information for the plurality ofprecoding codebook parameters, a first precoding matrix indicator (PMI)and a second PMI, wherein the first PMI includes one or two codebookindices. The transceiver is further configured to transmit the CSIreporting on an uplink channel, the CSI reporting including thedetermined first and second PMIs.

In another embodiment, a base station (BS) is provided. The BS includesa transceiver and a processor operably connected to the transceiver. Theprocessor is configured to configure a UE with a CSI reporting;configure the UE with a plurality of precoding codebook parameters;cause the transceiver to transmit configuration information for the CSIreporting and precoding codebook parameters; and receive a CSI reportfrom the UE including codebook indices from a first and a second PMIs.

In another embodiment, a method for operating a UE is provided. Themethod includes receiving, by the UE, configuration information for aCSI reporting including a plurality of precoding codebook parameters; inresponse to receipt of the configuration information for the CSIreporting and the configuration information for the plurality ofprecoding codebook parameters, determining, by the UE, a first precodingmatrix indicator (PMI) and a second PMI, wherein the first PMI includesone or two codebook indices; and transmitting, by the UE, the CSIreporting on an uplink channel, the CSI reporting including thedetermined first and second PMIs.

Other technical features may be readily apparent to one skilled in theart from the following figures, descriptions, and claims.

Before undertaking the DETAILED DESCRIPTION below, it can beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document. The term “couple” and its derivativesrefer to any direct or indirect communication between two or moreelements, whether or not those elements are in physical contact with oneanother. The terms “transmit,” “receive,” and “communicate,” as well asderivatives thereof, encompass both direct and indirect communication.The terms “include” and “comprise,” as well as derivatives thereof, meaninclusion without limitation. The term “or” is inclusive, meaningand/or. The phrase “associated with,” as well as derivatives thereof,means to include, be included within, interconnect with, contain, becontained within, connect to or with, couple to or with, be communicablewith, cooperate with, interleave, juxtapose, be proximate to, be boundto or with, have, have a property of, have a relationship to or with, orthe like. The term “controller” means any device, system or part thereofthat controls at least one operation. Such a controller can beimplemented in hardware or a combination of hardware and software and/orfirmware. The functionality associated with any particular controllercan be centralized or distributed, whether locally or remotely. Thephrase “at least one of,” when used with a list of items, means thatdifferent combinations of one or more of the listed items can be used,and only one item in the list can be needed. For example, “at least oneof: A, B, and C” includes any of the following combinations: A, B, C, Aand B, A and C, B and C, and A and B and C.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for other certain words and phrases are provided throughoutthis patent document. Those of ordinary skill in the art shouldunderstand that in many if not most instances, such definitions apply toprior as well as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates an example wireless network according to variousembodiments of the present disclosure;

FIGS. 2A and 2B illustrate example wireless transmit and receive pathsaccording to various embodiments of the present disclosure;

FIG. 3A illustrates an example user equipment according to variousembodiments of the present disclosure;

FIG. 3B illustrates an example enhanced NodeB (eNB) according to variousembodiments of the present disclosure;

FIG. 4 illustrates example two-dimensional (2D) antenna arraysconstructed from 16 dual-polarized elements arranged in a 4×2 or 2×4rectangular format which can be utilized in various embodiments of thepresent disclosure;

FIG. 5 illustrates an example CSI calculation procedure which respondsto a CSI-RS resource pattern or codebook parameter and calculates atwo-dimensional PMI/RI for two-dimensional pattern;

FIG. 6 illustrates an example CSI calculation procedure which respondsto a CSI-RS resource pattern or codebook parameter and a PMI/RIconfiguration for a second dimension;

FIG. 7 illustrates an example CSI calculation procedure which respondsto a CSI-RS resource pattern or codebook parameter and assumes awideband PMI with RI=1 for a second dimension;

FIG. 8 illustrates an example method wherein a UE receives configurationinformation containing at least a CSI reporting configuration andcodebook parameters and reports a first PMI composed of either one ortwo codebook indices conditioned on at least two codebook parameters.

FIG. 9 illustrates an example method wherein an eNB configures a UE withCSI reporting and codebook parameters and in turn receives a CSI reportincluding at least CQI, RI, a first PMI, and a second PMI wherein thenumber of codebook indices associated with the first PMI is conditionedon at least two codebook parameters.

DETAILED DESCRIPTION

FIGS. 1 through 10, discussed below, and the various embodiments used todescribe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure can beimplemented in any suitably arranged wireless communication system.

LIST OF ACRONYMS

2D: two-dimensional

MIMO: multiple-input multiple-output

SU-MIMO: single-user MIMO

MU-MIMO: multi-user MIMO

3GPP: 3rd generation partnership project

LTE: long-term evolution

UE: user equipment

eNB: evolved Node B or “eNB”

DL: downlink

UL: uplink

CRS: cell-specific reference signal(s)

DMRS: demodulation reference signal(s)

SRS: sounding reference signal(s)

UE-RS: UE-specific reference signal(s)

CSI-RS: channel state information reference signals

SCID: scrambling identity

MCS: modulation and coding scheme

RE: resource element

CQI: channel quality information

PMI: precoding matrix indicator

RI: rank indicator

MU-CQI: multi-user CQI

CSI: channel state information

CSI-IM: CSI interference measurement

CoMP: coordinated multi-point

DCI: downlink control information

UCI: uplink control information

PDSCH: physical downlink shared channel

PDCCH: physical downlink control channel

PUSCH: physical uplink shared channel

PUCCH: physical uplink control channel

PRB: physical resource block

RRC: radio resource control

AoA: angle of arrival

AoD: angle of departure

The following documents and standards descriptions are herebyincorporated by reference into the present disclosure as if fully setforth herein: 3GPP Technical Specification (TS) 36.211 version 12.4.0,“E-UTRA, Physical channels and modulation” (“REF 1”); 3GPP TS 36.212version 12.3.0, “E-UTRA, Multiplexing and Channel coding” (“REF 2”);3GPP TS 36.213 version 12.4.0, “E-UTRA, Physical Layer Procedures” (“REF3”); and 3GPP TS 36.331 version 12.4.0, “E-UTRA, Radio Resource Control(RRC) Protocol Specification” (“REF 4”).

FIG. 1 illustrates an example wireless network 100 according to variousembodiments of the present disclosure. The embodiment of the wirelessnetwork 100 shown in FIG. 1 is for illustration only. Other embodimentsof the wireless network 100 could be used without departing from thescope of the present disclosure. The wireless network 100 includes aneNB (eNB) 101, an eNB 102, and an eNB 103. The eNB 101 communicates withthe eNB 102 and the eNB 103. The eNB 101 also communicates with at leastone Internet Protocol (IP) network 130, such as the Internet, aproprietary IP network, or other data network. Depending on the networktype, other well-known terms can be used instead of “eNB” or “eNB,” suchas “base station” or “access point.” For the sake of convenience, theterms “eNB” and “eNB” are used in this patent document to refer tonetwork infrastructure components that provide wireless access to remoteterminals. Also, depending on the network type, other well-known termscan be used instead of “user equipment” or “UE,” such as “mobilestation,” “subscriber station,” “remote terminal,” “wireless terminal,”or “user device.” For the sake of convenience, the terms “userequipment” and “UE” are used in this patent document to refer to remotewireless equipment that wirelessly accesses an eNB, whether the UE is amobile device (such as a mobile telephone or smartphone) or is normallyconsidered a stationary device (such as a desktop computer or vendingmachine).

The eNB 102 provides wireless broadband access to the network 130 for afirst plurality of user equipments (UEs) within a coverage area 120 ofthe eNB 102. The first plurality of UEs includes a UE 111, which can belocated in a small business (SB); a UE 112, which can be located in anenterprise (E); a UE 113, which may be located in a WiFi hotspot (HS); aUE 114, which can be located in a first residence (R); a UE 115, whichmay be located in a second residence (R); and a UE 116, which can be amobile device (M) like a cell phone, a wireless laptop, a wireless PDA,or the like. The eNB 103 provides wireless broadband access to thenetwork 130 for a second plurality of UEs within a coverage area 125 ofthe eNB 103. The second plurality of UEs includes the UE 115 and the UE116. In some embodiments, one or more of the eNBs 101-103 cancommunicate with each other and with the UEs 111-116 using 5G, LTE,LTE-A, WiMAX, or other advanced wireless communication techniques.

Dotted lines show the approximate extents of the coverage areas 120 and125, which are shown as approximately circular for the purposes ofillustration and explanation only. It should be clearly understood thatthe coverage areas associated with eNBs, such as the coverage areas 120and 125, can have other shapes, including irregular shapes, dependingupon the configuration of the eNBs and variations in the radioenvironment associated with natural and man-made obstructions.

As described in more detail below, one or more of BS 101, BS 102 and BS103 include 2D antenna arrays as described in embodiments of the presentdisclosure. In some embodiments, one or more of BS 101, BS 102 and BS103 support channel quality measurement and reporting for systems having2D antenna arrays. In various embodiments, one or more of BSs 101-103and UEs 111-116 perform signaling, configuration and/or calculation forCSI reporting.

Although FIG. 1 illustrates one example of a wireless network 100,various changes can be made to FIG. 1. For example, the wireless network100 could include any number of eNBs and any number of UEs in anysuitable arrangement. Also, the eNB 101 could communicate directly withany number of UEs and provide those UEs with wireless broadband accessto the network 130. Similarly, each eNB 102-103 could communicatedirectly with the network 130 and provide UEs with direct wirelessbroadband access to the network 130. Further, the eNB 101, 102, and/or103 could provide access to other or additional external networks, suchas external telephone networks or other types of data networks.

FIGS. 2A and 2B illustrate example wireless transmit and receive pathsaccording to the present disclosure. In the following description, atransmit path 200 can be described as being implemented in an eNB (suchas eNB 102), while a receive path 250 can be described as beingimplemented in a UE (such as UE 116). However, it will be understoodthat the receive path 250 could be implemented in an eNB and that thetransmit path 200 could be implemented in a UE. In some embodiments, thereceive path 250 is configured to support channel quality measurementand reporting for systems having 2D antenna arrays as described inembodiments of the present disclosure.

The transmit path 200 includes a channel coding and modulation block205, a serial-to-parallel (S-to-P) block 210, a size N Inverse FastFourier Transform (IFFT) block 215, a parallel-to-serial (P-to-S) block220, an add cyclic prefix block 225, and an up-converter (UC) 230. Thereceive path 250 includes a down-converter (DC) 255, a remove cyclicprefix block 260, a serial-to-parallel (S-to-P) block 265, a size N FastFourier Transform (FFT) block 270, a parallel-to-serial (P-to-S) block275, and a channel decoding and demodulation block 280.

In the transmit path 200, the channel coding and modulation block 205receives a set of information bits, applies coding (such asconvolutional, Turbo, or low-density parity check (LDPC) coding), andmodulates the input bits (such as with Quadrature Phase Shift Keying(QPSK) or Quadrature Amplitude Modulation (QAM)) to generate a sequenceof frequency-domain modulation symbols. The serial-to-parallel block 210converts (such as de-multiplexes) the serial modulated symbols toparallel data in order to generate N parallel symbol streams, where N isthe IFFT/FFT size used in the eNB 102 and the UE 116. The size N IFFTblock 215 performs an IFFT operation on the N parallel symbol streams togenerate time-domain output signals. The parallel-to-serial block 220converts (such as multiplexes) the parallel time-domain output symbolsfrom the size N IFFT block 215 in order to generate a serial time-domainsignal. The ‘add cyclic prefix’ block 225 inserts a cyclic prefix to thetime-domain signal. The up-converter 230 modulates (such as up-converts)the output of the ‘add cyclic prefix’ block 225 to an RF frequency fortransmission via a wireless channel. The signal can also be filtered atbaseband before conversion to the RF frequency.

A transmitted RF signal from the eNB 102 arrives at the UE 116 afterpassing through the wireless channel, and reverse operations to those atthe eNB 102 are performed at the UE 116. The down-converter 255down-converts the received signal to a baseband frequency, and theremove cyclic prefix block 260 removes the cyclic prefix to generate aserial time-domain baseband signal. The serial-to-parallel block 265converts the time-domain baseband signal to parallel time domainsignals. The size N FFT block 270 performs an FFT algorithm to generateN parallel frequency-domain signals. The parallel-to-serial block 275converts the parallel frequency-domain signals to a sequence ofmodulated data symbols. The channel decoding and demodulation block 280demodulates and decodes the modulated symbols to recover the originalinput data stream.

As described in more detail below, the transmit path 200 or the receivepath 250 can perform signaling for a designed codebook. Each of the eNBs101-103 may implement a transmit path 200 that is analogous totransmitting in the downlink to UEs 111-116 and can implement a receivepath 250 that is analogous to receiving in the uplink from UEs 111-116.Similarly, each of UEs 111-116 may implement a transmit path 200 fortransmitting in the uplink to eNBs 101-103 and can implement a receivepath 250 for receiving in the downlink from eNBs 101-103.

Each of the components in FIGS. 2A and 2B can be implemented using onlyhardware or using a combination of hardware and software/firmware. As aparticular example, at least some of the components in FIGS. 2A and 2Bcan be implemented in software, while other components can beimplemented by configurable hardware or a mixture of software andconfigurable hardware. For instance, the FFT block 270 and the IFFTblock 215 can be implemented as configurable software algorithms, wherethe value of size N can be modified according to the implementation.

Furthermore, although described as using FFT and IFFT, this is by way ofillustration only and should not be construed to limit the scope of thepresent disclosure. Other types of transforms, such as Discrete FourierTransform (DFT) and Inverse Discrete Fourier Transform (IDFT) functions,could be used. It will be appreciated that the value of the variable Ncan be any integer number (such as 1, 2, 3, 4, or the like) for DFT andIDFT functions, while the value of the variable N can be any integernumber that is a power of two (such as 1, 2, 4, 8, 16, or the like) forFFT and IFFT functions.

Although FIGS. 2A and 2B illustrate examples of wireless transmit andreceive paths, various changes can be made to FIGS. 2A and 2B. Forexample, various components in FIGS. 2A and 2B could be combined,further subdivided, or omitted and additional components could be addedaccording to particular needs. Also, FIGS. 2A and 2B are meant toillustrate examples of the types of transmit and receive paths thatcould be used in a wireless network. Other suitable architectures couldbe used to support wireless communications in a wireless network.

FIG. 3A illustrates an example UE 116 according to the presentdisclosure. The embodiment of the UE 116 illustrated in FIG. 3A is forillustration only, and the UEs 111-115 of FIG. 1 could have the same orsimilar configuration. However, UEs come in a wide variety ofconfigurations, and FIG. 3A does not limit the scope of the presentdisclosure to any particular implementation of a UE.

The UE 116 includes an antenna 305, a radio frequency (RF) transceiver310, transmit (TX) processing circuitry 315, a microphone 320, andreceive (RX) processing circuitry 325. The UE 116 also includes aspeaker 330, a processor 340, an input/output (I/O) interface (IF) 345,an input 350, a display 355, and a memory 360. The memory 360 includesan operating system (OS) program 361 and one or more applications 362.

The RF transceiver 310 receives, from the antenna 305, an incoming RFsignal transmitted by an eNB of the network 100. The RF transceiver 310down-converts the incoming RF signal to generate an intermediatefrequency (IF) or baseband signal. The IF or baseband signal is sent tothe RX processing circuitry 325, which generates a processed basebandsignal by filtering, decoding, and/or digitizing the baseband or IFsignal. The RX processing circuitry 325 transmits the processed basebandsignal to the speaker 330 (such as for voice data) or to the processor340 for further processing (such as for web browsing data).

The TX processing circuitry 315 receives analog or digital voice datafrom the microphone 320 or other outgoing baseband data (such as webdata, e-mail, or interactive video game data) from the processor 340.The TX processing circuitry 315 encodes, multiplexes, and/or digitizesthe outgoing baseband data to generate a processed baseband or IFsignal. The RF transceiver 310 receives the outgoing processed basebandor IF signal from the TX processing circuitry 315 and up-converts thebaseband or IF signal to an RF signal that is transmitted via theantenna 305.

The processor 340 can include one or more processors or other processingdevices and execute the OS program 361 stored in the memory 360 in orderto control the overall operation of the UE 116. For example, processor340 could control the reception of forward channel signals and thetransmission of reverse channel signals by the RF transceiver 310, theRX processing circuitry 325, and the TX processing circuitry 315 inaccordance with well-known principles. In some embodiments, theprocessor 340 includes at least one microprocessor or microcontroller.

The processor 340 is also capable of executing other processes andprograms resident in the memory 360, such as operations for channelquality measurement and reporting for systems having 2D antenna arraysas described in embodiments of the present disclosure as described inembodiments of the present disclosure. The processor 340 can move datainto or out of the memory 360 as required by an executing process. Insome embodiments, the processor 340 is configured to execute theapplications 362 based on the OS program 361 or in response to signalsreceived from eNBs or an operator. The processor 340 is also coupled tothe I/O interface 345, which provides the UE 116 with the ability toconnect to other devices such as laptop computers and handheldcomputers. The I/O interface 345 is the communication path between theseaccessories and the processor 340.

The processor 340 is also coupled to the input 350 (e.g., keypad,touchscreen, button etc.) and the display 355. The operator of the UE116 can use the input 350 to enter data into the UE 116. The display 355can be a liquid crystal display or other display capable of renderingtext and/or at least limited graphics, such as from web sites.

The memory 360 is coupled to the processor 340. Part of the memory 360could include a random access memory (RAM), and another part of thememory 360 could include a Flash memory or other read-only memory (ROM).

As described in more detail below, the UE 116 can perform signaling andcalculation for CSI reporting. Although FIG. 3A illustrates one exampleof UE 116, various changes can be made to FIG. 3A. For example, variouscomponents in FIG. 3A could be combined, further subdivided, or omittedand additional components could be added according to particular needs.As a particular example, the processor 340 could be divided intomultiple processors, such as one or more central processing units (CPUs)and one or more graphics processing units (GPUs). Also, while FIG. 3Aillustrates the UE 116 configured as a mobile telephone or smartphone,UEs could be configured to operate as other types of mobile orstationary devices.

FIG. 3B illustrates an example eNB 102 according to the presentdisclosure. The embodiment of the eNB 102 shown in FIG. 3B is forillustration only, and other eNBs of FIG. 1 could have the same orsimilar configuration. However, eNBs come in a wide variety ofconfigurations, and FIG. 3B does not limit the scope of the presentdisclosure to any particular implementation of an eNB. eNB 101 and eNB103 can include the same or similar structure as eNB 102.

As shown in FIG. 3B, the eNB 102 includes multiple antennas 370 a-370 n,multiple RF transceivers 372 a-372 n, transmit (TX) processing circuitry374, and receive (RX) processing circuitry 376. In certain embodiments,one or more of the multiple antennas 370 a-370 n include 2D antennaarrays. The eNB 102 also includes a controller/processor 378, a memory380, and a backhaul or network interface 382.

The RF transceivers 372 a-372 n receive, from the antennas 370 a-370 n,incoming RF signals, such as signals transmitted by UEs or other eNBs.The RF transceivers 372 a-372 n down-convert the incoming RF signals togenerate IF or baseband signals. The IF or baseband signals are sent tothe RX processing circuitry 376, which generates processed basebandsignals by filtering, decoding, and/or digitizing the baseband or IFsignals. The RX processing circuitry 376 transmits the processedbaseband signals to the controller/processor 378 for further processing.

The TX processing circuitry 374 receives analog or digital data (such asvoice data, web data, e-mail, or interactive video game data) from thecontroller/processor 378. The TX processing circuitry 374 encodes,multiplexes, and/or digitizes the outgoing baseband data to generateprocessed baseband or IF signals. The RF transceivers 372 a-372 nreceive the outgoing processed baseband or IF signals from the TXprocessing circuitry 374 and up-converts the baseband or IF signals toRF signals that are transmitted via the antennas 370 a-370 n.

The controller/processor 378 can include one or more processors or otherprocessing devices that control the overall operation of the eNB 102.For example, the controller/processor 378 could control the reception offorward channel signals and the transmission of reverse channel signalsby the RF transceivers 372 a-372 n, the RX processing circuitry 376, andthe TX processing circuitry 374 in accordance with well-knownprinciples. The controller/processor 378 could support additionalfunctions as well, such as more advanced wireless communicationfunctions. In some embodiments, the controller/processor 378 includes atleast one microprocessor or microcontroller.

The controller/processor 378 is also capable of executing programs andother processes resident in the memory 380, such as an OS. Thecontroller/processor 378 is also capable of supporting channel qualitymeasurement and reporting for systems having 2D antenna arrays asdescribed in embodiments of the present disclosure. In some embodiments,the controller/processor 378 supports communications between entities,such as web RTC. The controller/processor 378 can move data into or outof the memory 380 as required by an executing process.

The controller/processor 378 is also coupled to the backhaul or networkinterface 382. The backhaul or network interface 382 allows the eNB 102to communicate with other devices or systems over a backhaul connectionor over a network. The interface 382 could support communications overany suitable wired or wireless connection(s). For example, when the eNB102 is implemented as part of a cellular communication system (such asone supporting 5G or new radio access technology or NR, LTE, or LTE-A),the interface 382 could allow the eNB 102 to communicate with other eNBsover a wired or wireless backhaul connection. When the eNB 102 isimplemented as an access point, the interface 382 could allow the eNB102 to communicate over a wired or wireless local area network or over awired or wireless connection to a larger network (such as the Internet).The interface 382 includes any suitable structure supportingcommunications over a wired or wireless connection, such as an Ethernetor RF transceiver.

The memory 380 is coupled to the controller/processor 378. Part of thememory 380 could include a RAM, and another part of the memory 380 couldinclude a Flash memory or other ROM. In certain embodiments, a pluralityof instructions, such as a BIS algorithm is stored in memory. Theplurality of instructions are configured to cause thecontroller/processor 378 to perform the BIS process and to decode areceived signal after subtracting out at least one interfering signaldetermined by the BIS algorithm.

As described in more detail below, the transmit and receive paths of theeNB 102 (implemented using the RF transceivers 372 a-372 n, TXprocessing circuitry 374, and/or RX processing circuitry 376) performconfiguration and signaling for CSI reporting.

Although FIG. 3B illustrates one example of an eNB 102, various changescan be made to FIG. 3B. For example, the eNB 102 could include anynumber of each component shown in FIG. 3. As a particular example, anaccess point could include a number of interfaces 382, and thecontroller/processor 378 could support routing functions to route databetween different network addresses. As another particular example,while shown as including a single instance of TX processing circuitry374 and a single instance of RX processing circuitry 376, the eNB 102could include multiple instances of each (such as one per RFtransceiver).

FIG. 4 depicts an example of a 2D dual-polarized antenna port array withM_(a) rows and N_(a) columns where (M_(a), N_(a))=(2,4) and (4,2) whichcan be utilized in one or more embodiments of the present disclosure.These arrangement results in a total of 2M_(a)N_(a)=16 ports, eachmapped to one CSI-RS port. The three indexings 400, 410, and 420 arethree examples in indexing the 16 antenna ports as a means of mappingantenna ports to precoding matrix elements. For row-first indexing 400,antenna ports associated with the same polarization group are indexed ina row-first manner regardless of (M_(a), N_(a)). For longer-firstindexing 410, antenna ports associated with the same polarization groupare indexed in a column-first manner when M_(a)>N_(a), but row-firstmanner when M_(a)≤N_(a). For shorter-first indexing 420, antenna portsassociated with the same polarization group are indexed in a row-firstmanner when M_(a)>N_(a), but column-first manner when M_(a)≤N_(a).Indexing 400 is therefore termed row-first indexing while indexing 410longer-first indexing and indexing 420 shorter-first indexing.

In these illustrative embodiments, both M_(a) and N_(a) can beconfigured by an eNB for a UE. In another example, rather than definingM_(a) and N_(a) as the number of rows and columns of the rectangulararray of ports or port pattern, respectively, these two parameters canbe defined as two-dimensional precoding codebook parameters. The valuesof M_(a) and N_(a) partly determine the manner in which a codebook(hence each precoding matrix element in the codebook) is mapped ontoantenna ports of a one- or two-dimensional antenna array. Thisconfiguration can be performed with and without signaling the totalnumber of antenna ports. When a UE is configured with a codebook, theseparameters can be included either in a corresponding CSI processconfiguration or NZP (non-zero-power) CSI-RS resource configuration.

In legacy LTE systems, precoding codebooks are utilized for CSIreporting. Two categories of CSI reporting modes are supported:PUSCH-based aperiodic CSI (A-CSI) and PUCCH-based periodic CSI (P-CSI).In each category, different modes are defined based on frequencyselectivity of CQI and/or PMI, that is, whether wideband (one CSIparameter calculated for all the “set S subbands”) or subband (one CSIparameter calculated for each “set S subband”) reporting is performed.The supported CSI reporting modes are given in TABLE 1 and 2.

TABLE 1 CQI and PMI Feedback Types for PUSCH (Aperiodic) CSI ReportingModes PMI Feedback Type No Single Multiple PMI PMI PMI PUSCH CQIWideband Mode 1-2 Feedback (wideband CQI) Type UE Selected Mode 2-0 Mode2-2 (subband CQI) Higher Layer- Mode 3-0 Mode 3-1 Mode 3-2 configured(subband CQI)

TABLE 2 CQI and PMI Feedback Types for PUCCH (Periodic) CSI ReportingModes PMI Feedback Type No PMI Single PMI PUCCH CQI Wideband Mode 1-0Mode 1-1 Feedback Type (wideband CQI) UE Selected Mode 2-0 Mode 2-1(subband CQI)

Designing a CSI reporting mechanism which attains high accuracy with areasonably low feedback overhead is challenging as more antenna portsare utilized. Especially relevant is an ability to adapt to long-termchannel statistics including DL AoD profile. Unlike short-term channelcoefficients, under certain circumstances it is possible to measurelong-term channel statistics at an eNB even for FDD. Provided that UL-DLduplex distance is not too large, UL-DL long-term reciprocity holds andallows an eNB to measure DL AoD profile from uplink signals. If, forsome reason, such a measurement scheme is infeasible, a low-rate CSIreporting which contains an indication of DL AoD profile can beemployed. Therefore, there is a need to design codebooks for CSIreporting and its associated CSI reporting procedures, which slowlyadapts to long-term channel statistics while maintaining low feedbackoverhead.

Furthermore, to support two-dimensional precoding, straightforwardextensions such as configuring a CSI reporting mode for each of the twodimensions independently and applying the same CSI reporting mode alongwith its associated configurations for both dimensions are eitherinefficient (resulting in too many CSI reporting modes) or restrictive(neglecting potential differences between horizontal and verticaldimensions). Therefore, there is a need to extend the CSI reportingmodes given in TABLE 1 and 2 in a manner which avoids the above twodrawbacks. This entails refined definition of each of the CSI reportingmodes as well as each of the CSI parameters. This also entailsfacilitating flexible support of PMI reporting granularity, that is,independent configurations for each of the two (for example, horizontaland vertical) dimensions.

A precoding matrix or a precoder, which can be used by an eNB (such as102) to perform short-term precoding for transmitting to a UE andassumed by a UE to derive a CSI report, can be described as a dual-stageprecoding matrix:

W=W ₁ W ₂  (Equation 1)

Referring to FIG. 4, the size of the precoding matrix W is N_(TX)×N_(L)where N_(TX)=2M_(a)N_(a), is the total number of antenna or CSI-RS portsand N_(L) is the number of transmission layers (also termed the rank).The first-stage precoder W₁ pertains to a long-term component and isassociated with long-term channel statistics. In addition, W₁ iswideband (the same W₁ for all the set S subbands). The second-stageprecoder W₂ pertains to a short-term component which performs selection,co-phasing, or any linear operation to W₁. Therefore, the number ofcolumns of W₁ can be perceived as the number of basis vectors N_(b) forW₂. In addition, W₂ can be either wideband (the same W₂ for all the setS subbands) or subband (one W₂ for each set S subband).

For 2D (two-dimensional) rectangular port array, each of the first andthe second stage precoders can be described as a Kronecker product of afirst and a second precoder. In the present disclosure, A⊗B denotes theKronecker product between two matrices A and B. This example embodimentis termed the full Kronecker Product (full KP) codebook. The subscriptsm and n in W_(m,n)(i_(m,n)) denote precoding stage (first or second) anddimension (first or second, such as vertical or horizontal),respectively. Each of the precoders W_(m,n) is a function of an indexwhich serves as a PMI component. Thus, the precoding matrix W can bedescribed in terms of 4 PMI components i_(1,1), i_(1,2), i_(2,1),i_(2,2) as follows.

$\begin{matrix}{{W\left( {i_{1,1},i_{1,2},i_{2,1},i_{2,2}} \right)} = {{\left( {{W_{1,1}\left( i_{1,1} \right)}{W_{2,1}\left( i_{2,1} \right)}} \right) \otimes \left( {{W_{1,2}\left( i_{1,2} \right)}{W_{2,2}\left( i_{2,2} \right)}} \right)} = {\left( {{W_{1,1}\left( i_{1,1} \right)} \otimes {W_{1,2}\left( i_{1,2} \right)}} \right)\left( {{W_{2,1}\left( i_{2,1} \right)} \otimes {W_{2,2}\left( i_{2,2} \right)}} \right)}}} & \left( {{Equation}\mspace{14mu} 2} \right)\end{matrix}$

Given a precoding codebook (a set of precoding matrices W(i_(1,1),i_(1,2), i_(2,1), i_(2,2))), a UE measures a CSI-RS in a subframedesignated to carry CSI-RS, calculates a CSI (including PMI, RI, and CQIwhere each of these three CSI parameters can include multiplecomponents) based on the measurement, and reports the calculated CSI toa serving eNB 102. This PMI represents an index of a recommendedprecoding matrix in the precoding codebook. Different precodingcodebooks can be used for different values of RI.

Another example embodiment assumes that a precoder in a designatedcodebook can be described in (3), termed the partial Kronecker Product(partial KP) codebook. The subscripts m and n in W_(m,n)(i_(m,n)) denoteprecoding stage (first or second stage) and dimension (first or seconddimension), respectively. Each of the precoding matrices W_(m,n) is afunction of an index which serves as a PMI component. Thus, theprecoding matrix W can be described as a function of 3 PMI componentsi_(1,1), i_(1,2), i₂ as follows.

W(i _(1,1) ,i _(1,2) ,i ₂)=(W _(1,1)(i _(1,1))⊗W _(1,2)(i _(1,2)))(W ₂(i₂))  (Equation 3)

Similar to the previous codebook embodiment, a UE measures a CSI-RS in asubframe designated to carry CSI-RS, calculates a CSI (including PMI,RI, and CQI where each of these three CSI parameters can includemultiple components) based on the measurement, and reports thecalculated CSI to a serving eNB 102.

In either of the above two embodiments, the number of columns of W_(1,1)and W_(1,2) can be perceived as the number of basis vectors, or thenumber of spatial beams associated with a first and a second dimensions,N_(b,1) and N_(b,2) for the second-stage precoder(s). To adapt tochanges in long-term channel statistics such as AoD profiles, these twoparameters can be configurable for a UE. Changing the values of N_(b,1)and N_(b,2) amounts to reconfiguring the codebook for the UE.Configuring these parameters can also be done implicitly, such as byconfiguring a codebook selection parameter which corresponds to at leastone of these two codebook parameters.

In the present disclosure, depending on the configured CSI-RS portpattern or the value of precoding codebook or codebook subset parametersreceived by a UE, the UE determines the manner in which CSI calculationand reporting is performed. This includes, for example, whether a 1D(one-dimensional) or a 2D (two-dimensional) CSI calculation andreporting is to be performed. As previously mentioned, such CSI-RS portpattern or precoding codebook parameters can include M_(a) and/or N_(a).

Although CSI-RS port pattern or codebook parameters are sufficient indetermining the manner in which CSI calculation and reporting isperformed, a new transmission mode (TM)—termed, for instance, TM x—whichsupports FD-MIMO and transmission with 2D antenna array can also bedefined and used in conjunction with the CSI-RS port pattern orprecoding parameters to determine the manner in which CSI calculationand reporting is performed.

For instance, if a UE is not configured for TM x, 1D CSI calculation andreporting according to legacy LTE (such as Rel.12) specification isperformed. If a UE is configured for TM x, if it is inferred thatM_(a)=1 or N_(a)=1 (either from a CSI-RS port pattern parameter orcodebook or codebook subset parameters such as M_(a) or N_(a)), 1D CSIreporting is performed (which can include 1D codebooks for PMI reportingin addition to those already supported in legacy Rel.12 LTEspecification). Else, 2D CSI calculation and reporting is performed.When 1D CSI reporting is performed, the CSI reporting modes in TABLE 1and 2 (hence the associated definition of CQI, PMI, and RI) are definedaccording to legacy Rel.12 LTE specification (see e.g., REF3 section7.2). On the other hand, when 2D CSI reporting is performed, severalextensions of the CSI reporting modes in TABLE 1 and 2 are given below.

If the Kronecker precoding structure defined in equation (2) is utilized(where W₂ can be described in terms of the Kronecker product of twoprecoders associated with two dimensions), then the following CSIreporting parameters are used. First, PMI/RI parameters i_(2,V),i_(1,V), v-RI for vertical dimension and i_(2,H), i_(1,H), h-RI forhorizontal dimension. Alternatively, the four PMI values can be denotedas {i_(1,1), i_(1,2), i_(2,1), i_(2,2)}. Here, i_(m,n) denotes PMIassociated with the m-th stage precoding (m=1, 2) and n-th dimension(note that the first dimension is not necessarily vertical). Second, CQIparameter. A single CQI entity (including one or two CQI valuesdepending on the number of codewords) which is calculated conditioned onvertical and horizontal (or the first-dimension and thesecond-dimension) PMI/RI parameters.

If the Kronecker precoding structure defined in equation (3) is utilized(where W₂ is not described in terms of the Kronecker product of twoprecoders associated with two dimensions), then the following CSIreporting parameters are used. First, PMI/RI parameters i_(1,V) forvertical dimension; i_(1,H) for horizontal dimension; i₂ and RIassociated with both dimensions. Alternatively, the three PMI values canbe denoted as {i_(1,1), i_(1,2), i₂}. Here, i_(1,n) denotes PMIassociated with the first-stage precoding and n-th dimension (note thatthe first dimension is not necessarily vertical). Second, CQI parameter.A single CQI entity which is calculated conditioned upon vertical andhorizontal (or the first-dimension and the second-dimension,respectively) PMI/RI parameters.

In both cases, coupling between RI and PMI, at least for each dimension,takes place since a codebook is associated with a given transmissionrank hypothesis. A UE calculates a single CQI entity for bothdimensions, in contrast to two separate CQI entities, to avoid CSImismatch at a serving eNB. Therefore, two separate CSI reporting modeconfigurations, each for one dimension, are unnecessary and in factresult in performance loss.

Below are several exemplary embodiments, each corresponding to adistinct extension of the CSI reporting modes given in TABLE 1 and 2,where only one CSI reporting mode configuration is utilized for bothhorizontal and vertical (first and second) dimensions. In the followingembodiments, only one CQI entity is calculated at a UE for bothdimensions conditioned upon all the PMI/RI parameters. Each embodimentcorresponds to a different PMI/RI construction for supporting 2D CSI-RSport pattern or 2D NZP CSI-RS resource or 2D codebook parameters.

In a first CSI reporting embodiment, a joint 2D (two-dimensional) PMI/RIis calculated and reported for 2D CSI-RS port pattern or codebookconfiguration. In this embodiment, one RI value associated with bothdimensions and two sets of PMI are defined. The first PMI set includesthe first-stage or first PMI i₁ which represents {i_(1,H), i_(1,V)} or{i_(1,1), i_(1,2)} encoded jointly. The second PMI set includes thesecond-stage or second PMI i₂ which either represents {i_(2,H), i_(2,V)}or {i_(2,1), i_(2,2)} encoded jointly for precoding structure inequation (2), or i simply a single index i₂ for precoding structure inequation (3). In this solution, a same reporting granularity (in timeand frequency) is applied to all the PMI parameters for both dimensions.Therefore, the same description for the different CSI reporting modes inREF3 section 7.2 directly applies.

The joint PMI parameters i₂ (if applicable) and i₁ can be defined withrespect to one-dimensional PMIs. An example of such a definition for i₁is given in TABLE 3 below. For illustrative purposes, the associated 1Dcodebook size is assumed to be 16. An analogous definition can beapplied to i₂ if applicable (for instance, when precoder description inequation (2) is utilized). In the two exemplary tables of TABLE 3, afirst dimension is associated with horizontal and a second dimensionvertical (such as indexing 400 in FIG. 4). Other associations arepossible. For example, if indexing 410 in FIG. 4 is assumed, the firstdimension is associated with the shorter of the two dimensions. Else ifindexing 420 in FIG. 4 is assumed, the first dimension is associatedwith the longer of the two dimensions. Else, any of these two dimensionsis not associated with any particular dimension. In any of theseexamples, the tables below can be applied with the correspondingdimension association.

TABLE 3 Two exemplary definitions of joint 2D (a) i₁ for 2D CSI-RS porti₁ for the first i₁ for the second pattern or 2D codebook dimension(i_(1, 1)) dimension (i_(1, 2))  0 0 0  1 1 . . . . . . 15 15  16 1 0 171 . . . . . . 31 15  . . . . . . . . . 240  15  0 241  1 . . . . . .255  15  (b) i₁ for 2D CSI-RS port i₁ for the second i₁ for the firstpattern or 2D codebook dimension (i_(1, 2)) dimension (i_(1, 1))  0 0 0 1 1 . . . 15 15  16 1 0 17 1 . . . 31 15  . . . . . . . . . 240  15  0241  1 . . . . . . 255  15 

In the example described in TABLE 3(a), the first PMI i₁ is constructedfrom concatenating the first PMI field i_(1,1) and the second PMI fieldi_(1,2). Since the first PMI is signaled as a binary-valued codewordformed by a sequence of bits, the first PMI codeword i₁ is constructedfrom [i_(1,1) i_(1,2)]. Written in terms of a bit sequence, thiscodeword can be described as b_(1,0), b_(1,1), . . . , b_(1,L) ₁ ⁻¹,b_(2,0), b_(2,1), . . . , b_(2,L) ₂ ⁻¹ where b_(1,0), b_(1,1), . . . ,b_(1,L) ₁ ⁻¹ is the bit sequence associated with or binaryrepresentation of i_(1,1) (wherein b_(1,0) is the most significant bitand b_(1,L) ₁ ⁻¹ the least significant bit of this bit sequence) andb_(2,0), b_(2,1), . . . , b_(2,L) ₂ ⁻¹ is the bit sequence associatedwith or binary representation of i_(1,2) (wherein b_(2,0) is the mostsignificant bit and b_(2,L) ₂ ⁻¹ the least significant bit of this bitsequence). Likewise, in the example described in TABLE 3(b), the firstPMI i₁ is constructed from concatenating the second PMI field i_(1,2)and the first PMI field i_(1,1). Since the first PMI is signaled as abinary-valued codeword formed by a sequence of bits, the first PMIcodeword i₁ is constructed from [i_(1,2) i_(1,1)]. Written in terms of abit sequence, this codeword can be described as b_(2,0), b_(2,1), . . ., b_(2,L) ₂ ⁻¹, b_(1,0), b_(1,1), . . . , b_(1,L) ₁ ⁻¹ where b_(1,0),b_(1,1), . . . , b_(1,L) ₂ ⁻¹ is the bit sequence associated with orbinary representation of i_(1,1) (wherein b_(1,0) is the mostsignificant bit and b_(1,L) ₁ ⁻¹ the least significant bit of this bitsequence) and b_(2,0), b_(2,1), . . . , b_(2,L) ₂ ⁻¹ is the bit sequenceassociated with or binary representation of i_(1,2) (wherein b_(2,0) isthe most significant bit and b_(2,L) ₂ ⁻¹ the least significant bit ofthis bit sequence).

This joint definition and encoding method for reporting the first PMI i₁can be utilized for or in conjunction with any CSI calculation/reportingmethod pertaining to 2D CSI-RS port pattern or 2D precoding codebookwhere the first PMI i₁ includes two codebook indices associated with twodimensions. Therefore, it is also applicable to other CSIcalculation/reporting embodiments in the present disclosure.

For PUSCH-based aperiodic CSI reporting, the frequency granularity ofPMI reporting inherent in a given CSI reporting mode (either widebandPMI, UE-selected sub-band PMI, or eNB-configured sub-band PMI) appliesto each of the 2D PMI parameter(s). Since A-CSI is reported by a UE upona request from a serving eNB, time granularity is not an issue. ForPUCCH-based periodic CSI reporting mode 1-1, only wideband PMI isreported. Therefore, frequency granularity is not an issue. Timegranularity follows the relation between i₁ and i₂ for a given P-CSIreporting mode. For example, P-CSI mode 1-1 submode 1 allows i₁ and i₂to be configured with different periodicities. For P-CSI mode 1-1submode 2, the same periodicity applies to i₁ and i₂ since they arereported together.

FIG. 5 illustrates an example CSI calculation procedure 500 whichresponds to a CSI-RS resource pattern or codebook parameter andcalculates a two-dimensional PMI/RI for two-dimensional pattern. In thisexample, transmission mode configuration is used in conjunction withCSI-RS port pattern or codebook parameters M_(a) and N_(a). However,this example method can operate without transmission mode configuration.Upon receiving a transmission mode configuration 501 and a CSI-RSresource pattern configuration 505, a UE determines whether the patternis 1D or 2D (515) if the UE is configured for a certain correspondingtransmission mode. The criterion in embodiment 515 utilizes a CSI-RSport pattern or codebook parameters or codebook subset parameters suchas M_(a) or N_(a). If it is associated with 1D configuration, a 1DPMI/RI definition such as the one given in section 7.2 of REF3 is used(530). Else, a 2D joint PMI/RI definition is used (520). In case of 2Dconfiguration, this 2D joint PMI/RI corresponds to the horizontal (H)and vertical (V) dimensions—or a first and a second dimension—of theCSI-RS port pattern or codebook configuration. Having determined thedimensionality of PMI/RI, the UE calculates CSI in 525 given a CSIreporting mode configuration from a serving eNB (510).

While this CSI reporting mode extension is simple, it is restrictivesince it imposes the same time and frequency granularity for PMIreporting in both dimensions. In some notable cases, horizontal andvertical array dimensions can experience different channelcharacteristics. The next embodiment partially addresses this issue.

In a second CSI reporting embodiment, the time and/or frequencygranularity of PMI reporting for one of the dimensions is configurablefor a UE. Since a single CQI entity is computed for dimensions, the CSIreporting modes given in TABLE 1 and 2 can be extended for 2D CSI-RSport pattern or codebook configuration via configuring time and/orfrequency granularity of PMI reporting associated with one of the twodimensions. The choice of the two dimensions (whether the first or thesecond dimension) whose time and/or frequency granularity of PMIreporting is configurable can be configured via higher-layer or RRCsignaling. Alternatively, this choice can be fixed. For example, it canbe fixed to the second dimension.

This second embodiment allows some additional flexibility over the timeand/or frequency granularity of PMI reporting associated with each ofthe CSI reporting modes. The granularity inherent in the configured CSIreporting mode is applied to the other dimension—in this example, thefirst dimension. Configurable frequency granularity (wideband PMI orsub-band PMI) is applicable only for PUSCH-based aperiodic CSI reporting(A-CSI) given in TABLE 1. Configurable time granularity (reportingperiodicity) is applicable only for PUCCH-based periodic CSI reporting(P-CSI) given in TABLE 2. This configuration can be performed by aserving eNB and signaled to the UE via higher-layer (RRC) signaling. Asan example, this configuration parameter can be termedPMI_TF_Granularity_2ndD_freq and PMI_TF_Granularity_2ndD_time.

FIG. 6 illustrates an example CSI calculation procedure 600 whichresponds to a CSI-RS resource pattern or codebook parameters and aPMI/RI configuration for a second dimension. In this example,transmission mode configuration is used in conjunction with CSI-RS portpattern or codebook parameters M_(a) and N_(a). However, this examplemethod can operate without transmission mode configuration. Uponreceiving a transmission mode configuration 601 and a CSI-RS portpattern or codebook parameter configuration 605, the UE determineswhether the pattern is 1D or 2D (615) if the UE is configured for acertain corresponding transmission mode. The criterion in thedetermination in 615 utilizes a CSI-RS port pattern or codebookparameters or codebook subset parameters such as M_(a) or N_(a). If itis associated with 1D configuration, a 1D PMI/RI definition such as theone given in section 7.2 of REF3 is used (620). Else, a 2D joint PMI/RIdefinition is used (625). In case of 2D CSI-RS port pattern, the UEreceives and decodes the PMI granularity for a second dimension in 625from a configuration parameter 607 (for instance,PMI_TF_Granularity_2ndD_freq and PMI_TF_Granularity_2ndD_time fromhigher-layer signaling). Having determined the dimensionality of PMI/RI,the UE calculates CSI in 630 given a CSI reporting mode configuration610 from a serving eNB. The PMI granularity for a first dimension isinferred from the CSI reporting mode configuration 610.

An exemplary assignment for the first and second dimension is horizontal(H) and vertical (V), respectively. If indexing 410 is used, the firstdimension is associated with the shorter of the two dimensions. Else, ifindexing 420 is used, the first dimension is associated with the longerof the two dimensions. Else, any of these two dimensions is notassociated with any particular dimension.

For dual-stage precoding structure in equation (2), the first-stageprecoding matrix W₁ is a wideband precoder. Therefore, frequencygranularity given in the RRC parameter PMI_TF_Granularity_2ndD_freqassociated with a second dimension only applies to W₂ when a UE reportsPUSCH-based aperiodic CSI. Then it is applicable when W₂ can bedescribed as a Kronecker product between horizontal and vertical (or afirst dimension and a second dimension) precoding matrices (such as thedescription in equation (2)). At least two alternatives can be used forPMI_TF_Granularity_2ndD_freq. A first alternative is a one-bit indicatorfor the second dimension which selects between wideband PMI (calculatedassuming transmission on the set S subbands) and subband PMI (calculatedassuming transmission on the given subband). A second alternative is aone-bit indicator for the second dimension which selects between thedefault PMI granularity given by the choice of A-CSI reporting mode andits alternative PMI granularity. For example, for A-CSI mode 3-2, ifPMI_TF_Granularity_2ndD_freq is set to default (e.g. 0), the PMIassociated with the second dimension is subband. Otherwise, ifPMI_TF_Granularity_2ndD_freq is set to alternative (e.g. 1), the PMIassociated with the second dimension is wideband.

In terms of time granularity, PMI_TF_Granularity_2ndD_time configuresthe time granularity of PUCCH-based periodic CSI reporting. Fordual-stage precoding structure in equation (2), this applies to W₁associated with a second dimension W_(1,2). It also applies to for thesecond dimension of W₂ if W₂ can be described as a Kronecker productbetween horizontal and vertical precoding matrices (or a first dimensionand a second dimension). For 2D CSI-RS port pattern, this applies, forexample, when the horizontal and vertical components of W₂ can beseparated as exemplified in the precoder structure in equation (2).

Some exemplary specifications for this embodiment are given below. Here(M_(a), N_(a)) represent 2D CSI-RS port pattern or codebook parametersfor a given NZP CSI-RS resource where M_(a) and N_(a) are associatedwith a first and a second dimension, respectively. Two RRC parametersPMI_TF_Granularity_2ndD_time and PMI_TF_Granularity_2ndD_freq configurethe time and frequency granularity as described above. The seconddimension is assumed to be vertical. These definitions are exemplary andillustrative. For example, the criterion in embodiment for determiningbetween 1D and 2D utilizes a CSI-RS port pattern or codebook parametersor codebook subset parameters such as M_(a) or N_(a). In addition, ifindexing 410 is used, the first dimension is associated with the shorterof the two dimensions. Else, if indexing 420 is used, the firstdimension is associated with the longer of the two dimensions. In thatcase, {i_(1,V), i_(1,H), i_(2,V), i_(2,H)} can be replaced by {i_(1,1),i_(1,2), i_(2,1), i_(2,2)} or {i_(1,2), i_(1,1), i_(2,2), i_(2,1)}.Furthermore, if precoding description in equation (3) is used instead of(2), {i_(2,V), i_(2,H)} is substituted with a single index i₂.Furthermore, {i_(1,V), i_(1,H), i₂} is replaced by {i_(1,1), i_(1,2),i₂} or {i_(1,2), i_(1,1), i₂}. Moreover, ‘horizontal codebook’ can berenamed ‘a first codebook’ and ‘vertical codebook can be renamed ‘asecond codebook.’ These definitions describe only the componentsapplicable to the use of 2D CSI-RS port pattern or codebook.

For example, for PUSCH-based aperiodic CSI reporting (see e.g., TABLE1), mode 1-2 can be described as follows:

-   -   For each subband a preferred first-dimension (for instance,        horizontal) precoding matrix is selected from the        first-dimension codebook subset assuming transmission only in        the subband        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=WIDEBAND, a single preferred            second-dimension (for instance, vertical) precoding matrix            is selected from the second-dimension codebook subset            assuming transmission on set S subbands.        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=SUBBAND, a preferred            second-dimension precoding matrix is selected from the            second-dimension codebook subset assuming transmission only            in the subband.    -   A UE reports one wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        first-dimension and second-dimension precoding matrices.    -   A UE reports the following precoding matrix indicators:        -   If M_(a)=1 or N_(a)=1, a first precoding matrix indicator            for all set S subbands and a second precoding matrix            indicator for each set S subband.        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=WIDEBAND, a first            first-dimension and second-dimension precoding matrix            indicator i_(1,H) and i_(1,V) for the set S subbands, a            second first-dimension precoding matrix indicator i_(2,H)            for each set S subband, and a second second-dimension            precoding matrix indicator i_(2,V) for the set S subbands        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=SUBBAND, a first            first-dimension and second-dimension precoding matrix            indicator i_(1,H) and i_(1,V) for the set S subbands, a            second first-dimension precoding matrix indicator i_(2,H)            for each set S subband, and a second second-dimension            precoding matrix indicator i_(2,V) for each set S subband            -   If precoding structure in equation (3) is used instead                of (2), i_(2,H) and i_(2,V) for each set S subband are                replaced by i₂ for each set S subband    -   Subband size is given by Table 7.2.1-3 in REFS.    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.        Mode 3-1 can be described as follows:    -   A single first-dimension (for instance, horizontal) precoding        matrix is selected from the first-dimension codebook subset        assuming transmission on set S subbands        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=WIDEBAND, a single preferred            second-dimension (for instance, vertical) precoding matrix            is selected from the second-dimension codebook subset            assuming transmission on set S subbands.        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=SUBBAND, a preferred            second-dimension precoding matrix is selected from the            second-dimension codebook subset assuming transmission only            in the subband.    -   A UE reports one subband CQI value per codeword for each set S        subband which are calculated assuming the use of the        corresponding selected first-dimension and second-dimension        precoding matrices and assuming transmission in the        corresponding subband.    -   A UE reports a wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        first-dimension and second-dimension precoding matrices    -   A UE reports the following precoding matrix indicators:        -   If M_(a)=1 or N_(a)=1, a first and second precoding matrix            indicator corresponding to the selected single precoding            matrix.        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=WIDEBAND, a first            first-dimension and second-dimension precoding matrix            indicator i_(1,H) and i_(1,V) for the set S subbands, a            second first-dimension and second-dimension precoding matrix            indicator i_(2,H) and i_(2,V) for the set S subbands            -   If precoding structure in equation (3) is used instead                of (2), i_(2,H) and i_(2,V) for the set S subbands are                replaced by i₂ for the set S subbands        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=SUBBAND, a first            first-dimension and second-dimension precoding matrix            indicator i_(1,H) and i_(1,V) for the set S subbands, a            second first-dimension precoding matrix indicator i_(2,H)            for the set S subbands, and a second second-dimension            precoding matrix indicator i_(2,V) for each set S subband    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.        Mode 3-2 can be described as follows:    -   For each subband a preferred first-dimension (for instance,        horizontal) precoding matrix is selected from the        first-dimension codebook subset assuming transmission only in        the subband        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=WIDEBAND, a single preferred            second-dimension (for instance, vertical) precoding matrix            is selected from the second-dimension codebook subset            assuming transmission on set S subbands.        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=SUBBAND, a preferred            second-dimension precoding matrix is selected from the            second-dimension codebook subset assuming transmission only            in the subband.    -   A UE reports a wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        first-dimension and second-dimension precoding matrices.    -   A UE reports the following precoding matrix indicators:        -   If M_(a)=1 or N_(a)=1, a first precoding matrix indicator            for all set S subbands and a second precoding matrix            indicator for each set S subband.        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=WIDEBAND, a first            first-dimension and second-dimension precoding matrix            indicator i_(1,H) and i_(1,V) for the set S subbands, a            second first-dimension precoding matrix indicator i_(2,H)            for each set S subband, and a second second-dimension            precoding matrix indicator i_(2,V) for the set S subbands        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=SUBBAND, a first            first-dimension and second-dimension precoding matrix            indicator i_(1,H) and i_(1,V) for the set S subbands, a            second first-dimension precoding matrix indicator i_(2,H)            for each set S subband, and a second second-dimension            precoding matrix indicator i_(2,V) for each set S subband            -   If precoding structure in equation (3) is used instead                of (2), i_(2,H) and i_(2,V) for each set S subband are                replaced by i₂ for each set S subband    -   A UE reports one subband CQI value per codeword for each set S        subband which are calculated assuming the use of the        corresponding selected first-dimension and second-dimension        precoding matrices and assuming transmission in the        corresponding subband.    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.        Description for mode 2-2 is analogous to the above description        for modes 2-1, 3-1, and 3-2 and one of ordinary skill in the art        would be able to derive the full description for mode 2-2 based        on the above description for modes 2-1, 3-1, and 3-2.

An alternative embodiment for PUSCH-based aperiodic CSI mode 3-1 can bemade by constraining the vertical PMI (or a second dimension PMI) to bewideband. This is applicable when, for instance, vertical channelvariability is less than that of horizontal. In this case,PMI_TF_Granularity_2ndD_freq is not used. Therefore, mode 3-1 can bedescribed as follows:

-   -   A single first-dimension (for instance, horizontal) precoding        matrix is selected from the first-dimension codebook subset        assuming transmission on set S subbands        -   If M_(a)>1 and N_(a)>1, a single preferred second-dimension            (for instance, vertical) precoding matrix is selected from            the second-dimension codebook subset assuming transmission            on set S subbands.    -   A UE reports one subband CQI value per codeword for each set S        subband which are calculated assuming the use of the        corresponding selected first-dimension and second-dimension        precoding matrices and assuming transmission in the        corresponding subband.    -   A UE reports a wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        first-dimension and second-dimension precoding matrices    -   A UE reports the following precoding matrix indicators:        -   If M_(a)=1 or N_(a)=1, a first and second precoding matrix            indicator corresponding to the selected single precoding            matrix.        -   If M_(a)>1 and N_(a)>1, a first first-dimension and            second-dimension precoding matrix indicator i_(1,H) and            i_(1,V) for the set S subbands, a second first-dimension and            second-dimension precoding matrix indicator i_(2,H) and            i_(2,H) for the set S subbands            -   If precoding structure in equation (3) is used instead                of (2), i_(2,H) and i_(2,V) for the set S subbands are                replaced by i₂ for the set S subbands    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.

In a third CSI reporting embodiment, dual-stage precoding is appliedonly on one of the two dimensions. While such one dimension can beeither horizontal or vertical, in some deployment scenarios, thehorizontal dimension tends to exhibit more time variation. Therefore,single-stage precoding is applied on the vertical (in this example,second) dimension.

In this case, a feature to configure a UE not to report at least oneparticular PMI parameter can be introduced. For example, a single-stageprecoding can be performed on vertical dimension by turning off thesecond stage precoder W_(2,V) and setting v-RI (rank indicatorassociated with the vertical dimension) to 1. Thus, one-stage widebandvertical precoding is used. This precoder structure (assumed for CSIreporting) can be described as follows (assuming indexing 410 in FIG.4). Here, horizontal is assumed to be the first dimension and verticalthe second dimension.

$\begin{matrix}\begin{matrix}{W = {\left( {W_{1,H} \otimes w_{1,V}} \right)W_{2,H}}} \\{= {\left( {W_{1,H}W_{2,H}} \right) \otimes w_{1,V}}} \\{= {\left( {W_{1,H} \otimes w_{1,V}} \right)W_{2}}} \\{= {\left( {W_{1,H}W_{2}} \right) \otimes w_{1,V}}}\end{matrix} & \left. {{Equation}\mspace{14mu} 4} \right)\end{matrix}$

In this embodiment, the RRC configuration mechanism ofPMI_TF_Granularity_2ndD_freq is not applicable.

In terms of time granularity, PMI_TF_Granularity_2ndD_time is stillapplicable and configures the time granularity of PUCCH-based periodicCSI reporting. For dual-stage precoding matrix in (2), this applies toW₁ associated with a second dimension.

FIG. 7 illustrates an example CSI calculation procedure 700 whichresponds to a CSI-RS resource pattern or codebook parameter and assumesa wideband PMI with RI=1 for a second dimension. In this example,transmission mode configuration is used in conjunction with CSI-RS portpattern or codebook parameters M_(a) and N_(a). However, this examplemethod can operate without transmission mode configuration. Uponreceiving a transmission mode configuration 701 and a CSI-RS portpattern configuration or codebook parameters 705, the UE determineswhether the pattern is associated with 1D or 2D (715) if the UE isconfigured for a certain corresponding transmission mode. The criterionin the determination in 715 utilizes a CSI-RS port pattern parameter orcodebook parameters or codebook subset parameters such as M_(a) orN_(a). If it is associated with 1D pattern, a 1D PMI/RI definition suchas the one given in section 7.2 of REF3 is used (720). Else, a 2D jointPMI/RI definition is used where a single-stage wideband precoding isapplied for a second dimension as described above (725). Since thefirst-stage PMIs granularity is always wideband and the second-stage PMIfor the second dimension is non-existent, the PMI granularity for thesecond dimension in 725 is always wideband. That is, when single-stagewideband precoding is the only option for the second dimension (in thisexample, vertical) precoding, PMI_TF_Granularity_2ndD_freq is notneeded. Only

PMI_TF_Granularity_2ndD_time applies to P-CSI reporting (707). Havingdetermined the dimensionality of PMI/RI, the UE calculates CSI in 730given a CSI reporting mode configuration 710 from a serving eNB. The PMIgranularity for a first dimension is inferred from the CSI reportingmode configuration 710. An exemplary assignment for the first and seconddimension is horizontal (H) and vertical (V), respectively.

Some exemplary specifications for this embodiment are given below. Here(M_(a), N_(a)) represent 2D CSI-RS port pattern or codebook parametersfor a given NZP CSI-RS resource where M_(a) and N_(a) are associatedwith a first and a second dimension, respectively. One RRC parametersPMI_TF_Granularity_2ndD_time configures the time granularity asdescribed above. The second dimension is assumed to be vertical. Thesedefinitions are exemplary and illustrative. For example, the criterionin embodiment for determining between 1D and 2D utilizes a CSI-RS portpattern or codebook parameters or codebook subset parameters such asM_(a) or N_(a). In addition, if indexing 410 is used, the firstdimension is associated with the shorter of the two dimensions. Else, ifindexing 420 is used, the first dimension is associated with the longerof the two dimensions. In that case, {i_(1,V), i_(1,H), i_(2,H)} can bereplaced by {i_(1,1), i_(1,2), i_(2,1)} or {i_(1,2), i_(1,1), i_(2,2)}.Furthermore, if precoding description in equation (3) is used instead of(2), {i_(2,H), i_(2,V)} is substituted with a single index i₂.Furthermore, {i_(1,V), i_(1,H), i₂} is replaced by {i_(1,1), i_(1,2),i₂} or {i_(1,2), i_(1,1), i₂} Moreover, ‘horizontal codebook’ can berenamed ‘a first codebook’ and ‘vertical codebook can be renamed ‘asecond codebook.’ These definitions describe only the componentsapplicable to the use of 2D CSI-RS port pattern or codebook.

For example, for PUSCH-based aperiodic CSI reporting (see e.g., TABLE1), mode 1-2 can be described as follows:

-   -   For each subband a preferred first-dimension (for instance,        horizontal) precoding matrix is selected from the        first-dimension codebook subset assuming transmission only in        the subband        -   If M_(a)>1 and N_(a)>1, a preferred second-dimension            precoding matrix is selected from the second-dimension            codebook subset assuming transmission only in the subband.    -   A UE reports one wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        first-dimension and second-dimension precoding matrices.    -   A UE reports the following precoding matrix indicators:        -   If M_(a)=1 or N_(a)=1, a first precoding matrix indicator            for all set S subbands and a second precoding matrix            indicator for each set S subband.        -   If M_(a)>1 and N_(a)>1, a first first-dimension and            second-dimension precoding matrix indicator i_(1,H) and            i_(1,V) for the set S subbands, a second first-dimension            precoding matrix indicator i_(2,H) (or i₂) for each set S            subband    -   Subband size is given by Table 7.2.1-3 of REFS.    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.        Mode 3-1 can be described as follows:    -   A single first-dimension (for instance, horizontal) precoding        matrix is selected from the first-dimension codebook subset        assuming transmission on set S subbands        -   If M_(a)>1 and N_(a)>1, a single preferred second-dimension            (for instance, vertical) precoding matrix is selected from            the rank-one second-dimension codebook subset assuming            transmission on set S subbands.    -   A UE reports one subband CQI value per codeword for each set S        subband which are calculated assuming the use of the        corresponding selected first-dimension and second-dimension        precoding matrices and assuming transmission in the        corresponding subband.    -   A UE reports a wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        first-dimension and second-dimension precoding matrices    -   A UE reports the following precoding matrix indicators:        -   If M_(a)=1 or N_(a)=1, a first and second precoding matrix            indicator corresponding to the selected single precoding            matrix.        -   If M_(a)>1 and N_(a)>1, a first first-dimension and            second-dimension precoding matrix indicator i_(1,H) and            i_(1,V) for the set S subbands, a second first-dimension            i_(2,H) (or i₂) for the set S subbands    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.        Mode 3-2 can be described as follows:    -   For each subband a preferred first-dimension (for instance,        horizontal) precoding matrix is selected from the        first-dimension codebook subset assuming transmission only in        the subband        -   If M_(a)>1 and N_(a)>1, a preferred second-dimension            precoding matrix is selected from the second-dimension            codebook subset assuming transmission only in the subband.    -   A UE reports a wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        first-dimension and second-dimension precoding matrices.    -   A UE reports the following precoding matrix indicators:        -   If M_(a)=1 or N_(a)=1, a first precoding matrix indicator            for all set S subbands and a second precoding matrix            indicator for each set S subband.        -   If M_(a)>1 and N_(a)>1, a first first-dimension and            second-dimension precoding matrix indicator i_(1,H) and            i_(1,V) for the set S subbands, a second first-dimension            precoding matrix indicator i_(2,H) (or i₂) for each set S            subband    -   A UE reports one subband CQI value per codeword for each set S        subband which are calculated assuming the use of the        corresponding selected first-dimension and second-dimension        precoding matrices and assuming transmission in the        corresponding subband.    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.        Description for mode 2-2 is analogous to the above description        for modes 2-1, 3-1, and 3-2 and one of ordinary skill in the art        would be able to derive the full description for mode 2-2 based        on the above description for modes 2-1, 3-1, and 3-2.

In a fourth CSI reporting embodiment, the CSI reporting modes in TABLE 1and 2 are extended for supporting beamformed (BF) CSI-RS or ‘CLASS B’ or‘beamformed’ eMIMO-Type with one NZP CSI-RS resource. Therefore, when aUE receives BF CSI-RS from a serving eNB or is configured with ‘CLASS B’(‘beamformed’) eMIMO-Type, the UE can be configured to report PMIparameters associated with W₂ without W₁. In this case, CSI reporting isdone similarly to single-stage precoding. For example, as the UEreceives and decodes an RRC parameter which configures the UE for eitherbeamformed CSI-RS reception (or ‘CLASS B’ (‘beamformed’) eMIMO-Type) orturning OFF any PMI reporting associated with W₁, the UE performs CSIreporting associated with single-stage precoding. In this case, RI/PMIdefinition, but only that which is associated with W₂, from eitherembodiment 1, 2, or 3 is applicable.

Exemplary descriptions which correspond to this embodiment are givenbelow. The second dimension is assumed to be vertical. These definitionsare exemplary and illustrative. It is assumed that the number ofbeamformed CSI-RS ports is already acquired by the UE. This number ofports determines the horizontal and/or vertical codebooks associatedwith W₂ (hence i_(2,H) and i_(2,V)). Moreover, ‘horizontal codebook’ canbe renamed ‘a first codebook’ and ‘vertical codebook can be renamed ‘asecond codebook.’ For PUSCH-based aperiodic CSI reporting (see e.g.,TABLE 1), mode 1-2 can be described as follows:

-   -   For each subband a preferred first-dimension (for instance,        horizontal) precoding matrix is selected from the        first-dimension codebook subset assuming transmission only in        the subband        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=WIDEBAND, a single preferred            second-dimension (for instance, vertical) precoding matrix            is selected from the second-dimension codebook subset            assuming transmission on set S subbands.        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=SUBBAND, a preferred            second-dimension precoding matrix is selected from the            second-dimension codebook subset assuming transmission only            in the subband.    -   A UE reports one wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        first-dimension and second-dimension precoding matrices.    -   A UE reports the following precoding matrix indicators:        -   If M_(a)=1 or N_(a)=1, a second precoding matrix indicator            for each set S subband.        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=WIDEBAND, a second            first-dimension precoding matrix indicator i_(2,H) for each            set S subband, and a second second-dimension precoding            matrix indicator i₂, for the set S subbands        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=SUBBAND, a second            first-dimension precoding matrix indicator i_(2,H) for each            set S subband, and a second second-dimension precoding            matrix indicator i₂, for each set S subband    -   Subband size is given by Table 7.2.1-3 of REFS.    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.        Mode 3-1 can be described as follows:    -   A single first-dimension (for instance, horizontal) precoding        matrix is selected from the first-dimension codebook subset        assuming transmission on set S subbands        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=WIDEBAND, a single preferred            second-dimension (for instance, vertical) precoding matrix            is selected from the second-dimension codebook subset            assuming transmission on set S subbands.        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=SUBBAND, a preferred            second-dimension precoding matrix is selected from the            second-dimension codebook subset assuming transmission only            in the subband.    -   A UE reports one subband CQI value per codeword for each set S        subband which are calculated assuming the use of the        corresponding selected first-dimension and second-dimension        precoding matrices and assuming transmission in the        corresponding subband.    -   A UE reports a wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        first-dimension and second-dimension precoding matrices    -   A UE reports the following precoding matrix indicators:        -   If M_(a)=1 or N_(a)=1, a second precoding matrix indicator            corresponding to the selected single precoding matrix.        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=WIDEBAND, a second            first-dimension and second-dimension precoding matrix            indicator i_(2,H) and i_(2,V) for the set S subbands        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=SUBBAND, a second            first-dimension precoding matrix indicator i_(2,H) for the            set S subbands, and a second second-dimension precoding            matrix indicator i_(2,V) for each set S subband    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.        Mode 3-2 can be described as follows:    -   For each subband a preferred first-dimension (for instance,        horizontal) precoding matrix is selected from the        first-dimension codebook subset assuming transmission only in        the subband        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=WIDEBAND, a single preferred            second-dimension (for instance, vertical) precoding matrix            is selected from the second-dimension codebook subset            assuming transmission on set S subbands.        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=SUBBAND, a preferred            second-dimension precoding matrix is selected from the            second-dimension codebook subset assuming transmission only            in the subband.    -   A UE reports a wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        first-dimension and second-dimension precoding matrices.    -   A UE reports the following precoding matrix indicators:        -   If M_(a)=1 or N_(a)=1, a first precoding matrix indicator            for all set S subbands and a second precoding matrix            indicator for each set S subband.        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=WIDEBAND, a second            first-dimension precoding matrix indicator i_(2,H) for each            set S subband, and a second second-dimension precoding            matrix indicator i₂, for the set S subbands        -   If M_(a)>1 and N_(a)>1 and            PMI_TF_Granularity_2ndD_freq=SUBBAND, a second            first-dimension precoding matrix indicator i_(2,H) for each            set S subband, and a second second-dimension precoding            matrix indicator i₂, for each set S subband    -   A UE reports one subband CQI value per codeword for each set S        subband which are calculated assuming the use of the        corresponding selected first-dimension and second-dimension        precoding matrices and assuming transmission in the        corresponding subband.    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.        Description for mode 2-2 is analogous to the above description        for modes 2-1, 3-1, and 3-2 and one of ordinary skill in the art        would be able to derive the full description for mode 2-2 based        on the above description for modes 2-1, 3-1, and 3-2.

An alternative embodiment for PUSCH-based aperiodic CSI mode 3-1 can bemade by constraining the vertical PMI (or, the PMI associated with oneof the two dimensions) to be wideband. This is applicable when verticalchannel variability is less than that of horizontal. In this case,PMI_TF_Granularity_2ndD_freq is not used. In this case, mode 3-1 can bedescribed as follows:

-   -   A single first-dimension (for instance, horizontal) precoding        matrix is selected from the first-dimension codebook subset        assuming transmission on set S subbands        -   If M_(a)>1 and N_(a)>1, a single preferred second-dimension            (for instance, vertical) precoding matrix is selected from            the second-dimension codebook subset assuming transmission            on set S subbands.    -   A UE reports one subband CQI value per codeword for each set S        subband which are calculated assuming the use of the        corresponding selected first-dimension and second-dimension        precoding matrices and assuming transmission in the        corresponding subband.    -   A UE reports a wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        first-dimension and second-dimension precoding matrices    -   A UE reports the following precoding matrix indicators:        -   If M_(a)=1 or N_(a)=1, a second precoding matrix indicator            corresponding to the selected single precoding matrix.        -   If M_(a)>1 and N_(a)>1, a second first-dimension and            second-dimension precoding matrix indicator i_(2,H) and            i_(2,V) for the set S subbands    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.

Furthermore, if precoder structure in equation (3) is used instead of(2), i can be replaced by {i₂}. In this case, there is no need for acriterion to differentiate between 1D and 2D. Moreover, only a singleprecoding codebook is used. For PUSCH-based aperiodic CSI reporting (seee.g., TABLE 1), mode 1-2 can be described as follows:

-   -   For each subband a preferred precoding matrix is selected from        the codebook subset assuming transmission only in the subband        -   If PMI_TF_Granularity_2ndD_freq=WIDEBAND, a single preferred            precoding matrix is selected from the codebook subset            assuming transmission on set S subbands.        -   If PMI_TF_Granularity_2ndD_freq=SUBBAND, a preferred            precoding matrix is selected from the codebook subset            assuming transmission only in the subband.    -   A UE reports one wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        precoding matrix.    -   A UE reports the following precoding matrix indicators:        -   If PMI_TF_Granularity_2ndD_freq=WIDEBAND, a second precoding            matrix indicator i₂ for each set S subband        -   If PMI_TF_Granularity_2ndD_freq=SUBBAND, a second precoding            matrix indicator i₂ for each set S subband    -   Subband size is given by Table 7.2.1-3 of REFS.    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.        Mode 3-1 can be described as follows:    -   A single precoding matrix is selected from the codebook subset        assuming transmission on set S subbands        -   If PMI_TF_Granularity_2ndD_freq=WIDEBAND, a single preferred            precoding matrix is selected from the codebook subset            assuming transmission on set S subbands.        -   If PMI_TF_Granularity_2ndD_freq=SUBBAND, a preferred            precoding matrix is selected from the codebook subset            assuming transmission only in the subband.    -   A UE reports one subband CQI value per codeword for each set S        subband which are calculated assuming the use of the        corresponding selected precoding matrix and assuming        transmission in the corresponding subband.    -   A UE reports a wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        precoding matrix    -   A UE reports the following precoding matrix indicators:        -   If PMI_TF_Granularity_2ndD_freq=WIDEBAND, a second precoding            matrix indicator i₂ for each set S subband        -   If PMI_TF_Granularity_2ndD_freq=SUBBAND, a second precoding            matrix indicator i₂ for each set S subband    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.        Mode 3-2 can be described as follows:    -   For each subband a preferred precoding matrix is selected from        the codebook subset assuming transmission only in the subband        -   If PMI_TF_Granularity_2ndD_freq=WIDEBAND, a single preferred            precoding matrix is selected from the codebook subset            assuming transmission on set S subbands.        -   If PMI_TF_Granularity_2ndD_freq=SUBBAND, a preferred            precoding matrix is selected from the codebook subset            assuming transmission only in the subband.    -   A UE reports a wideband CQI value per codeword which is        calculated assuming the use of the corresponding selected        precoding matrix.    -   A UE report the following precoding matrix indicators:        -   If PMI_TF_Granularity_2ndD_freq=WIDEBAND, a second precoding            matrix indicator i₂ for each set S subband        -   If PMI_TF_Granularity_2ndD_freq=SUBBAND, a second precoding            matrix indicator i₂ for each set S subband    -   A UE report one subband CQI value per codeword for each set S        subband which are calculated assuming the use of the        corresponding selected precoding matrix and assuming        transmission in the corresponding subband.    -   For transmission modes 4, 8, 9, 10, and x the reported PMI and        CQI values are calculated conditioned on the reported RI. For        other transmission modes they are reported conditioned on rank        1.        Description for mode 2-2 is analogous to the above description        for modes 2-1, 3-1, and 3-2 and one of ordinary skill in the art        would be able to derive the full description for mode 2-2 based        on the above description for modes 2-1, 3-1, and 3-2.

In a fifth embodiment, departing from TABLE 1 and 2, CSI calculation andreporting for a given UE is fully configured and characterized with timeand/or frequency granularity parameters. Time granularity configurationcan include reporting periodicity/interval. Frequency granularityconfiguration can include a two-value indicator used to configure a UEwith either WIDEBAND or SUBBAND reporting. Alternatively, frequencygranularity configuration can include subband size (for example, interms of the number of RBs) wherein one possible value indicateswideband reporting (one report for all the RBs).

In one alternative of this embodiment, the time/frequency granularity ofCQI and PMI can be configured separately via higher-layer (RRC)signaling. For example, four RRC parameters CQI_T_Granularity,CQI_F_Granularity, PMI_T_Granularity, and PMI_F_Granularity can be usedto configure CSI calculation/reporting for a UE. As mentioned before,time granularity does not apply to A-CSI. Therefore, onlyCQI_F_Granularity and PMI_F_Granularity apply. If P-CSI is associatedwith wideband-only reporting, frequency granularity does not apply toP-CSI. Therefore, only CQI_T_Granularity and PMI_T_Granularity apply.

In another alternative of this embodiment, the time/frequencygranularity of CQI and PMI is configured jointly via higher-layer (RRC)signaling. For example, two RRC parameters CQIPMI_T_Granularity andCQIPMI_F_Granularity can be used to configure CSI calculation/reportingfor a UE. As mentioned before, time granularity does not apply to A-CSI.Therefore, only CQIPMI_F_Granularity applies. If P-CSI is associatedwith wideband-only reporting, frequency granularity does not apply toP-CSI. Therefore, only CQIPMI_T_Granularity applies.

In addition to the above, different PMI reporting granularities can beintroduced for two different dimensions when 2D CSI-RS port pattern or2D precoding codebook structure is used. For the first alternative, theRRC parameter PMI_T_Granularity can be substituted withPMI_T_Granularity_1stD and PMI_T_Granularity_2ndD whereas the RRCparameter PMI_F_Granularity can be substituted withPMI_F_Granularity_1stD and PMI_F_Granularity_2ndD. For dual-stageprecoder/codebook, different PMI reporting frequency granularities fordifferent dimensions applies for the structure in equation (2), but notfor the structure in equation (3).

FIG. 8 illustrates an example method 800 wherein a UE receivesconfiguration information containing at least a CSI reportingconfiguration and codebook parameters (801). The CSI reportingconfiguration can include a choice of CSI reporting mode. Two of thecodebook parameters are M_(a) and N_(a) which can correspond to thenumber of rows and columns in a two-dimensional dual-polarized portarray with a total of 2M_(a) N_(a) ports. In response to at least thecodebook parameters M_(a) and N_(a) (802), the UE calculates a first PMIi₁. If at least one of M_(a) and N_(a) equals to 1, i₁ includes onecodebook index associated with a first-stage precoding (805). If each ofM_(a) and N_(a) equals to a value greater than 1, i₁ includes twocodebook indices associated with a first-dimension i_(1,1) and asecond-dimension i_(1,2) of the first-stage precoding, respectively(810). In either case, the UE calculates a second PMI i₂ (806 and 811)and transmits a CSI report including at least CQI, RI, and {i₁, i₂} (807and 812).

FIG. 9 illustrates an example method 900 wherein an eNB configures a UE(labeled as UE-k for illustrative purposes) with CSI reporting andcodebook parameters (901). The CSI reporting configuration can include achoice of CSI reporting mode. Two of the codebook parameters are M_(a)and N_(a) which can correspond to the number of rows and columns in atwo-dimensional dual-polarized port array with a total of 2M_(a) N_(a)ports. The eNB transmits this configuration information to UE-k via a DLchannel (902). The eNB also receives a CSI report from UE-k (903), inresponse to the transmitted configuration information, which includes atleast a CQI, a RI, a first PMI, and a second PMI. Upon receiving the CSIreport, the eNB decodes the CQI, the RI, and a second-stage codebookindex from the second PMI (904). If at least one of M_(a) and N_(a)equals to 1 at 905, i₁ includes one codebook index associated with afirst-stage precoding (906). If each of M_(a) and N_(a) equals to avalue greater than 1, i₁ includes two codebook indices associated with afirst-dimension i_(1,1) and a second-dimension i_(1,2) of thefirst-stage precoding, respectively (907).

The above configuration information is signaled to the UE viahigher-layer or RRC signaling. At least one of the codebook parameterscan also be signaled to the UE via higher-layer or RRC signaling. Inanother example, signaling via a DL control channel can be used at leastfor one of the codebook parameters.

Although FIGS. 8 and 9 illustrate examples of processes for receivingconfiguration information and configuring a UE, respectively, variouschanges could be made to FIGS. 8 and 9. For example, while shown as aseries of steps, various steps in each figure could overlap, occur inparallel, occur in a different order, occur multiple times, or not beperformed in one or more embodiments.

Although the present disclosure has been described with an exampleembodiment, various changes and modifications can be suggested by or toone skilled in the art. It is intended that the present disclosureencompass such changes and modifications as fall within the scope of theappended claims.

What is claimed:
 1. A user equipment (UE) comprising: a transceiverconfigured to receive configuration information for a channel stateinformation (CSI) reporting, wherein the configuration informationincludes a plurality of precoding codebook parameters, the plurality ofprecoding codebook parameters including a number of antenna ports in afirst dimension and a second dimension; and a processor operablyconnected to the transceiver, the processor configured to determine, inresponse to receipt of the configuration information for the CSIreporting including the plurality of precoding codebook parameters, afirst precoding matrix indicator (PMI) and a second PMI, wherein thefirst PMI includes one codebook index when one of the number of antennaports in the first dimension and the second dimension equals one,wherein the first PMI includes two codebook indices when each of thenumber of antenna ports in the first dimension and the second dimensionis greater than one, and wherein the transceiver is further configuredto transmit the CSI reporting on an uplink channel, the CSI reportingincluding the determined first and second PMIs.
 2. The UE of claim 1,wherein: the two codebook indices of the first PMI are reported with asame frequency granularity and concatenated into a bit sequence.
 3. TheUE of claim 1, wherein a frequency granularity of a first codebook indexof the first PMI is separately configured from that of a second codebookindex of the first PMI for aperiodic CSI reporting.
 4. The UE of claim1, wherein the CSI reporting further includes a channel qualityindicator (CQI).
 5. The UE of claim 4, wherein a frequency granularityof the CQI is separately configured from that of the PMIs for aperiodicCSI reporting using two configuration parameters.
 6. The UE of claim 4,wherein time granularity of the CQI is separately configured from thatof the PMIs for periodic CSI reporting.
 7. The UE of claim 1, wherein afrequency granularity of a first of the one or two codebook indices ofthe first PMI is separately configured from that of a second of the oneor two codebook indices of the first PMI for aperiodic CSI reportingusing two configuration parameters.
 8. A base station (BS) comprising: atransceiver; and a processor operably connected to the transceiver, theprocessor configured to: generate a plurality of precoding codebookparameters, the plurality of precoding codebook parameters including anumber of antenna ports in a first dimension and a second dimension;cause the transceiver to transmit, to a user equipment (UE),configuration information for channel state information (CSI) reportingincluding the plurality of precoding codebook parameters; and receive aCSI report from the UE generated responsive to the transmittedconfiguration information transmitted from the BS, the CSI reportincluding codebook indices from first and second precoding matrixindicators (PMIs), wherein the first PMI includes one codebook indexwhen one of the number of antenna ports in the first dimension and thesecond dimension equals one, and wherein the first PMI includes twocodebook indices when each of the number of antenna ports in the firstdimension and the second dimension is greater than one.
 9. The BS ofclaim 8, wherein: the codebook indices of the first PMI within the CSIreport generated by the UE and received at the BS are reported with asame frequency granularity and concatenated into a bit sequence.
 10. TheBS of claim 8, wherein a frequency granularity of a first codebook indexof the first PMI within the CSI report generated by the UE and receivedat the BS is separately configured from that of a second codebook indexof the first PMI within the CSI report generated by the UE and receivedat the BS for aperiodic CSI reporting.
 11. The BS of claim 8, whereinthe CSI reporting further includes a channel quality indicator (CQI).12. The BS of claim 11, wherein a frequency granularity of the CQIwithin the CSI report generated by the UE and received at the BS isseparately configured from that of the first PMI within the CSI reportgenerated by the UE and received at the BS for aperiodic CSI reporting.13. The BS of claim 8, wherein a frequency granularity of a firstcodebook index of the first PMI within the CSI report generated by theUE and received at the BS is separately configured from that of a secondcodebook index of the first PMI within the CSI report generated by theUE and received at the BS for aperiodic CSI reporting using twoconfiguration parameters.
 14. A method for operating a user equipment(UE), the method comprising: receiving, by the UE, configurationinformation for a channel state information (CSI) reporting, wherein theconfiguration information includes a plurality of precoding codebookparameters, the plurality of precoding codebook parameters including anumber of antenna ports in a first dimension and a second dimension; andin response to receipt of the configuration information for the CSIreporting including the plurality of precoding codebook parameters,determining, by the UE, a first precoding matrix indicator (PMI) and asecond PMI, wherein the first PMI includes one codebook index when oneof the number of antenna ports in the first dimension and the seconddimension equals one, wherein the first PMI includes two codebookindices when each of the number of antenna ports in the first dimensionand the second dimension is greater than one, and transmitting, by theUE, the CSI reporting on an uplink channel, the CSI reporting includingthe determined first and second PMIs.
 15. The method of claim 14,wherein: the two codebook indices of the first PMI are reported with asame frequency granularity and concatenated into a bit sequence.
 16. Themethod of claim 14, wherein a frequency granularity of a first codebookindex of the first PMI is separately configured from that of a secondcodebook index of the first PMI for aperiodic CSI reporting.
 17. Themethod of claim 14, wherein the CSI reporting further includes a channelquality indicator (CQI).
 18. The method of claim 17, wherein a frequencygranularity of the CQI is separately configured from that of the PMI foraperiodic CSI reporting using two configuration parameters.
 19. Themethod of claim 17, wherein time granularity of the CQI is separatelyconfigured from that of the PMIs for periodic CSI reporting.
 20. Themethod of claim 14, wherein a frequency granularity of a first of theone or two codebook indices of the first PMI is separately configuredfrom that of a second of the one or two codebook indices of the firstPMI for aperiodic CSI reporting using two configuration parameters.